The purpose of this shared instrumentation grant is to obtain funds to purchase a Philips CM-lO Transmission Electron Microscope to be housed in a central electron microscopy unit that is being created in the Department of Molecular Biology at the Research Institute of Scripps Clinic. This facility will house at least two electron microscopes and related instrumentation. The Department of Molecular Biology is a new Department which has recently expanded into the area of cell biology. With this addition to the Department, there is a significant need for contemporary electron microscopic instrumentation. The Department currently has 43 full- time faculty members, and the present proposal represents a collective need for shared instrumentation immediately by 13 of these members. The Philips CM-lO Electron Microscope has been selected as the instrument for the request by the members of the internal advisory committee. This microscope was selected by the internal Advisory Committee because of their prior experience with this instrument and because of its capability for performing the various activities that will be required by this diverse set of users in the Department.